A component mounting apparatus in which a component is taken out from a component feeder by a mounting head and mounted on a mounting point on a substrate is known. The component mounting apparatus is provided with a component image capturing apparatus. This is because the image of the component held by the mounting head is captured by the component image capturing apparatus before the component is mounted on the substrate, whereby the holding state of the component by the mounting head is recognized and the component mounting posture or the like is corrected.
The component mounting apparatus of such a kind is disclosed, for example, in Japanese Patent No. 4381764. The component mounting apparatus disclosed in Japanese Patent No. 4381764 includes a component image capturing apparatus equipped with a camera for component recognition that incorporates a line sensor and a plurality of illumination units, and the component image capturing apparatus captures the image of the component by illuminating the component with one of the illumination units while moving the component at a predetermined speed relative to the camera. In this case, for a specific component, line images obtained under mutually different illumination conditions are arranged alternately, and twice as many line images are acquired by alternately switching two illumination units with different illumination conditions (illumination directions) and taking in the images while moving the components. Two component images with mutually different illumination conditions are simultaneously acquired, as the component is caused to pass only once by the camera, by extracting line images with the same illumination conditions from those images and combining the extracted images.
In the conventional component recognition apparatus such as described hereinabove, the component recognition rate apparently can be increased by increasing the movement speed of the component relative to the camera. However, where the component recognition rate is increased, the exposure time of each image capture line is shortened. As a result, the electric charge amount per each line image outputted from the line sensor is decreased and the image becomes dark and unclear. As a consequence, the component recognition accuracy can be reduced. In this case, the insufficient exposure apparently can be corrected by increasing the illumination intensity, but such a measure requires a large and expensive high-luminance illumination device, thereby increasing the size and cost of the apparatus, and cannot always be said to be effective.
In addition to the above-described acquisition of a plurality of images with different illumination conditions performed as the component is caused to pass only once by the camera, it is sometimes desirable, for example, to acquire component images of a plurality of types by receiving light beams with mutually different wavelengths under fixed illumination conditions, but such component images are difficult to acquire with the above-described component recognition apparatus.